Image processing apparatus, endoscope system, and operation method of image processing apparatus

ABSTRACT

An image acquisition unit acquires a medical image which is obtained by picking up an image of an observation target illuminated with illumination light including short-wavelength narrowband light, the observation target being magnified at a first magnification ratio or more and less than a second magnification ratio that is more than the first magnification ratio. A disease-related processing unit performs processing related to the disease on the basis of the medical image.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2020/025695 filed on 30 Jun. 2020, which claims priority under 35U.S.C § 119(a) to Japanese Patent Application No. 2019-127010 filed on 8Jul. 2019. The above application is hereby expressly incorporated byreference, in its entirety, into the present application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an image processing apparatus thatperforms processing related to a disease, an endoscope system, and anoperation method of an image processing apparatus.

2. Description of the Related Art

In the medical field, a medical image has been widely used fordiagnosis. For example, as an apparatus using a medical image, there isan endoscope system comprising a light source apparatus, an endoscope,and a processor apparatus. In the endoscope system, an observationtarget is irradiated with illumination light and an image of theobservation target illuminated with the illumination light is picked up,so that an endoscopic image as the medical image is acquired. Theendoscopic image is displayed on a monitor and used for diagnosis.

Further, in recent years, with processing performed on the basis of theendoscopic image, information that is used to support diagnosis, forexample, determination regarding a disease, such as a lesion, has beenalso provided to a user. For example, in JP2016-154810A, a featureamount is calculated from an endoscopic image, and classification (forexample, non-tumor, tumor, cancer, and SSA/P) corresponding topathological diagnosis is performed on the basis of the feature amount.

SUMMARY OF THE INVENTION

As a method of determining a disease, for example, there is a method ofdetermining a disease (for example, ulcerative colitis) on the basis ofa property of a microvessel or a bleeding area. In this case, sinceimaging with low magnification ratio of various elements of a livingbody, such as a microvessel or a bleeding area, makes the blood vesselor bleeding area imaged very small, it is difficult to extract the bloodvessel or bleeding area in a state in which the actual shape of theblood vessel or bleeding area is maintained, upon the extraction. On theother hand, in a case where the elements of the living body, such as themicrovessel or bleeding area are imaged at an excessively highmagnification ratio, not entire shape information of the elements of theliving body, as an observation target, but only local shape informationof the elements of the living body may be obtained. Therefore, it hasbeen required that a medical image in which the observation target isimaged at an appropriate magnification ratio is used, to enableextraction in a state in which the shape of the microvessel or bleedingarea is maintained and improvement of accuracy of processing related tothe disease.

JP2016-154810A describes that an image in which a tissue is magnified,for example, a 380 times magnified image is used as an endoscopic image.However, there is no description or suggestion of an appropriatemagnification ratio range for diagnostic imaging.

An object of the present invention is to provide an image processingapparatus, an endoscope system, and an operation method of an imageprocessing apparatus in which a medical image in which an observationtarget is imaged at an appropriate magnification ratio is used to enableextraction in a state in which a shape of a microvessel or a bleedingarea is maintained and improvement of accuracy of processing related toa disease.

According to the present invention, there is provided an imageprocessing apparatus comprising a processor, in which the processoracquires a medical image which is obtained by picking up an image of anobservation target illuminated with illumination light includingshort-wavelength narrowband light, the observation target beingmagnified at a first magnification ratio or more and less than a secondmagnification ratio that is more than the first magnification ratio, andperforms processing related to a disease on the basis of the medicalimage.

It is preferable that magnification of the observation target isperformed at the first magnification ratio, to make a thickness of ablood vessel that is included in the observation target magnified to oneor more pixels. The first magnification ratio is preferably five timesor more. The second magnification ratio is preferably 230 times or less.

The illumination light is preferably violet light of which a centralwavelength or a peak wavelength includes a wavelength of 410 nm, as theshort-wavelength narrowband light. It is preferable that theillumination light is blue narrowband light and green narrowband light,as the short-wavelength narrowband light, and the medical image isobtained by picking up an image of the observation target that isalternately illuminated with the blue narrowband light and the greennarrowband light. The illumination light is preferably pseudo whitelight including the short-wavelength narrowband light and fluorescenceobtained by irradiating a phosphor with excitation light. Theillumination light preferably includes violet light as theshort-wavelength narrowband light and blue light, green light, or redlight.

It is preferable that the processor performs at least one of calculatingan index value for a stage of ulcerative colitis, determining the stageof the ulcerative colitis, or determining pathological remission orpathological non-remission of the ulcerative colitis, on the basis of atleast one of superficial vascular congestion, intramucosal bleeding, orextramucosal bleeding that is obtained from the medical image.

According to the present invention, there is provided an endoscopesystem comprising: a light source unit that emits illumination lightincluding short-wavelength narrowband light; and a processor, in whichthe processor acquires a medical image which is obtained by picking upan image of an observation target illuminated with the illuminationlight, the observation target being magnified at a first magnificationratio or more and less than a second magnification ratio that is morethan the first magnification ratio, and performs processing related to adisease on the basis of the medical image.

According to the present invention, there is provided an operationmethod of an image processing apparatus in which a processor executes: astep of acquiring a medical image which is obtained by picking up animage of an observation target illuminated with illumination lightincluding short-wavelength narrowband light, the observation targetbeing magnified at a first magnification ratio or more and less than asecond magnification ratio that is more than the first magnificationratio; and a step of performing processing related to a disease on thebasis of the medical image.

According to the present invention, a medical image in which anobservation target is imaged at an appropriate magnification ratio isused to enable extraction in a state in which a shape of a microvesselor a bleeding area is maintained and improvement of accuracy ofprocessing related to a disease.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an appearance diagram of an endoscope system.

FIG. 2 is a block diagram showing a function of an endoscope systemaccording to a first embodiment.

FIG. 3 is a graph showing spectra of violet light V, blue light B, greenlight G, and red light R.

FIG. 4 is a graph showing a spectrum of special light according to thefirst embodiment.

FIG. 5 is a graph showing a spectrum of special light including onlyviolet light V.

FIG. 6 is a diagram illustrating a magnification ratio display sectionthat is displayed in a case where a magnification ratio is changedstepwise and a magnification ratio display section that is displayed ina case where a magnification ratio is continuously changed.

FIGS. 7A to 7E are diagrams illustrating a pattern of a vascularstructure that varies depending on severity of ulcerative colitis.

FIG. 8 is a cross-sectional view showing a cross-section of the largeintestine.

FIG. 9 is a block diagram showing a function of a disease-relatedprocessing unit.

FIG. 10 is an image diagram of a monitor that displays informationregarding determination.

FIGS. 11A and 11B are diagrams illustrating blood vessel extractionperformed on a special light image in a case where a thickness of ablood vessel is smaller than one pixel.

FIGS. 12A and 12B are diagrams illustrating blood vessel extractionperformed on a special light image in a case where the thickness of theblood vessel is one or more pixels.

FIG. 13 is a graph showing a relationship between an index value and apathological score in a case where a second magnification ratio is 40times.

FIG. 14 is a graph showing a relationship between an index value and apathological score in a case where the second magnification ratio is 135times.

FIG. 15 is an image diagram showing a special light image in which avascular density differs depending on a position.

FIG. 16 is a flowchart showing a series of flow of a disease-relatedprocessing mode.

FIG. 17 is a block diagram showing a function of an endoscope systemaccording to a second embodiment.

FIG. 18 is a plan view of a rotation filter.

FIG. 19 is a block diagram showing a function of an endoscope system ofa third embodiment.

FIG. 20 is a graph showing a spectrum of normal light according to thethird embodiment.

FIG. 21 is a graph showing a spectrum of special light according to thethird embodiment.

FIG. 22 is a block diagram showing a diagnosis support apparatus.

FIG. 23 is a block diagram showing a medical service support apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

In FIG. 1, an endoscope system 10 includes an endoscope 12, a lightsource apparatus 14, a processor apparatus 16, a monitor 18, and a userinterface 19. The endoscope 12 is optically connected to the lightsource apparatus 14 and electrically connected to the processorapparatus 16. The endoscope 12 includes an insertion part 12 a that isinserted into a body as an observation target, an operation part 12 bthat is provided in a proximal end part of the insertion part 12 a, anda bendable part 12 c and a distal end part 12 d that are provided on adistal end side of the insertion part 12 a. In a case where an angleknob 12 e of the operation part 12 b is operated, the bendable part 12 cis operated to be bent. In a case where the bendable part 12 c isoperated to be bent, the distal end part 12 d is directed in a desireddirection.

Further, the operation part 12 b is provided with a mode changeover SW(mode changeover switch) 12 f that is used for mode switching operation,a still image acquisition instruction portion 12 g that is used for anacquisition instruction of a still image of the observation target, anda zoom operation portion 12 h that is used for operation of a zoom lens43 (see FIG. 2), in addition to the angle knob 12 e.

The endoscope system 10 has three modes of a normal light mode, aspecial light mode, and a disease-related processing mode. In the normallight mode, an observation target is illuminated with normal light andan image thereof is picked up, so that a normal light image havingnatural color is displayed on a monitor 18. In the special light mode,the observation target is illuminated with special light having awavelength range different from the normal light and an image thereof ispicked up, so that a special light image in which a specific structureis enhanced is displayed on the monitor 18. In the disease-relatedprocessing mode, pathological remission or pathological non-remission ofulcerative colitis, which is one of the diseases, is determined on thebasis of the normal light image or the special light image. In thedisease-related processing mode, an index value for a stage ofulcerative colitis may be calculated, or the stage of ulcerative colitismay be determined.

In the present embodiment, a special light image (endoscopic image) isused in the disease-related processing mode, but a normal light imagemay be used. As the image that is used in the disease-related processingmode, a medical image, such as a radiography image that is obtained by aradiography apparatus, a CT image that is obtained by a computedtomography (CT) apparatus, and an MRI image obtained by a magneticresonance imaging (MRI), may be used, in addition to the special lightimage as the endoscopic image which is one of the medical images.Further, the processor apparatus 16 to which the endoscope 12 isconnected corresponds to an image processing apparatus according to thepresent invention, and the processor apparatus 16 executes thedisease-related processing mode, but the disease-related processing modemay be executed by another method. For example, an external imageprocessing apparatus different from the endoscope system 10 may beprovided with a function of a disease-related processing unit 66, theexternal image processing apparatus may execute the disease-relatedprocessing mode in response to input of the medical image, and theexecution result may be displayed on an external monitor connected tothe external image processing apparatus.

The processor apparatus 16 is electrically connected to the monitor 18and the user interface 19. The monitor 18 outputs and displays an imageof the observation target, information incidental to the image of theobservation target, and the like. The user interface 19 has a functionof receiving input operation, such as function settings. An externalrecording unit (not shown) that is used to record an image, imageinformation, or the like may be connected to the processor apparatus 16.Further, the processor apparatus 16 corresponds to the image processingapparatus according to the present invention.

In FIG. 2, the light source apparatus 14 comprises a light source unit20 and a light source control unit 21 that controls the light sourceunit 20. The light source unit 20 has, for example, a plurality ofsemiconductor light sources each of which is turned on or off, and in acase where the semiconductor light source is turned on, the light sourceunit 20 controls an amount of light emitted from each semiconductorlight source to emit illumination light with which the observationtarget is illuminated. In the present embodiment, the light source unit20 has four-color LEDs of a violet light emitting diode (V-LED) 20 a, ablue light emitting diode (B-LED) 20 b, a green light emitting diode(G-LED) 20 c, and a red light emitting diode (R-LED) 20 d.

As shown in FIG. 3, the V-LED 20 a generates violet light V having acentral wavelength of 405±10 nm and a wavelength range of 380 to 420 nm.The B-LED 20 b generates blue light B having a central wavelength of460±10 nm and a wavelength range of 420 to 500 nm. The G-LED 20 cgenerates green light G having a wavelength range of 480 to 600 nm. TheR-LED 20 d generates red light R having a central wavelength of 620 to630 nm and a wavelength range of 600 to 650 nm. The violet light V is ashort-wavelength narrowband light that is used to detect superficialvascular congestion, intramucosal bleeding, and extramucosal bleedingused in the disease-related processing mode, and a central wavelength ora peak wavelength thereof includes preferably a wavelength of 410 nm.

The light source control unit 21 controls the V-LED 20 a, the B-LED 20b, the G-LED 20 c, and the R-LED 20 d. Further, the light source controlunit 21 controls each of the LEDs 20 a to 20 d so that normal light ofwhich a light intensity ratio of violet light V, blue light B, greenlight G, and red light R is Vc:Bc:Gc:Rc is emitted, in the normal lightmode.

Further, the light source control unit 21 controls each of the LEDs 20 ato 20 d so that special light of which a light intensity ratio of violetlight V as the short-wavelength narrowband light, and blue light B,green light G, and red light R is Vs:Bs:Gs:Rs is emitted, in the speciallight mode and the disease-related processing mode. It is preferablethat a superficial blood vessel and the like are enhanced by the speciallight having the light intensity ratio of Vs:Bs:Gs:Rs. Therefore, infirst illumination light, it is preferable that the light intensity ofviolet light V is larger than the light intensity of the blue light B.For example, as shown in FIG. 4, the ratio of the light intensity Vs ofviolet light V to the light intensity Bs of blue light B is set to“4:1”. Alternatively, as shown in FIG. 5, for special light, the lightintensity ratio of violet light V, blue light B, green light G, and redlight R may be set to 1:0:0:0, and only the violet light V as theshort-wavelength narrowband light may be emitted.

In the present specification, the light intensity ratio includes a casewhere the ratio of at least one semiconductor light source is 0 (zero).Therefore, a case where any one or more of the semiconductor lightsources are not turned on is included. For example, even in a case whereonly one of the semiconductor light sources is turned on and the otherthree thereof is not turned on as in a case where the light intensityratio of violet light V, blue light B, green light G, and red light R is1:0:0:0, light is assumed to have the light intensity ratio.

The light emitted by each of the LEDs 20 a to 20 e is incident on alight guide 25 via an optical path coupling unit 23 that is formed of amirror, a lens, or the like. The light guide 25 is built in theendoscope 12 and the universal cord (cord that connects the endoscope 12to the light source apparatus 14 and the processor apparatus 16). Thelight guide 25 propagates the light from the optical path coupling unit23 to the distal end part 12 d of the endoscope 12.

The distal end part 12 d of the endoscope 12 is provided with anillumination optical system 30 a and an image pickup optical system 30b. The illumination optical system 30 a has an illumination lens 32, andthe observation target is irradiated with the illumination lightpropagated by the light guide 25 via the illumination lens 32. The imagepickup optical system 30 b has an objective lens 42 and an image pickupsensor 44. The light from the observation target irradiated with theillumination light is incident on the image pickup sensor 44, via theobjective lens 42 and a zoom lens 43. As a result, an image of theobservation target is formed on the image pickup sensor 44. The zoomlens 43 is a lens that is used to magnify the observation target, andthe zoom operation portion 12 h is operated, to move the zoom lens 43between a telephoto end and a wide-angle end.

In the present embodiment, the zoom lens 43 is used to change themagnification ratio stepwise. Here, the magnification ratio is a valuethat is obtained by dividing the size of an object displayed on themonitor 18 by the size of an actual object. For example, in a case wherethe monitor 18 is a 19-inch monitor, as shown in FIG. 6, themagnification ratio can be changed stepwise in two steps, three steps,and five steps, or the magnification ratio can be continuously changed.In order to display the magnification ratio in use on the monitor 18, amagnification ratio display section 47 that is displayed in a case wherethe magnification ratio is changed stepwise and a magnification ratiodisplay section 49 that is displayed in a case where the magnificationratio is continuously changed are provided at a specific displayposition of the monitor 18. In the magnification ratio display section47, the magnification ratio in use is represented by a combination offrameless display, framed display, and full display of boxes Bx1, Bx2,Bx3, and Bx4 provided between Near (N) representing a near field and Far(F) representing a far field. The size of the monitor 18 generally usedin the endoscope system 10 is 19 inches to 32 inches, and the widththereof is 23.65 cm to 39.83 cm.

Specifically, in a case where the magnification ratio is set to bechanged in two steps in which the magnification ratio is changed to 40times and 60 times, the frameless display is used for the boxes Bx1,Bx2, and Bx3, the framed display is used for the box Bx4 in a case ofthe magnification ratio in use of 40 times, and the full display is usedfor the box Bx4 in a case of the magnification ratio in use of 60 times.Alternatively, in a case where the magnification ratio is set to bechanged in three steps in which the magnification ratio is changed to 40times, 60 times, and 85 times, the frameless display is used for theboxes Bx1 and Bx2, and the framed display is used for the boxes Bx3 andBx4 in a case of the magnification ratio in use of 40 times. The frameddisplay is used for the box Bx3, and the full display is used for thebox Bx4 in a case of the magnification ratio in use of 60 times, and thefull display is used for the boxes Bx3 and Bx4 in a case of themagnification ratio in use of 85 times.

Alternatively, in a case where the magnification ratio is set to bechanged in five steps of 40 times, 60 times, 85 times, 100 times, and135 times, the framed display is used for the boxes Bx1, Bx2, Bx3, andBx4 in a case of the magnification ratio in use of 40 times. Further,the framed display is used for the boxes Bx1, Bx2, and Bx3, and the fulldisplay is used for the box Bx4 in a case of the magnification ratio inuse of 60 times. Further, the framed display is used for the boxes Bx1and Bx2, and the full display is used for the boxes Bx3 and Bx4 in acase of the magnification ratio of 85 times. Further, the framed displayis used for the box Bx1, and the full display is used for the boxes Bx2,Bx3, and Bx4 in a case of the magnification ratio of 100 times. Further,the full display is used for the boxes Bx1, Bx2, Bx3, and Bx4 in a caseof the magnification ratio of 135 times.

The magnification ratio display section 49 is provided with a horizontalbar 49 a provided between Near (N) representing a near field and Far (F)representing a far field. Only the frame of the horizontal bar 49 a isdisplayed until the magnification ratio becomes 40 times. In a casewhere the magnification ratio exceeds 40 times, the inside of the frameof the horizontal bar 49 a is displayed in specific color SC. Until themagnification ratio reaches 135 times, the region of the specific colorin the horizontal bar 49 a gradually expands to the N side as themagnification ratio is increased. In a case where the magnificationratio reaches 135 times, the region of the specific color expands to anupper limit display bar 49 b, and does not further expand to the N side.

As the image pickup sensor 44, a charge coupled device (CCD) imagepickup sensor or a complementary metal-oxide semiconductor (CMOS) imagepickup sensor may be used. Further, instead of the primary color imagepickup sensor 44, a complementary color image pickup sensor providedwith complementary color filters of cyan (C), magenta (M), yellow (Y),and green (G) may be used. In a case where the complementary color imagepickup sensor is used, image signals of the four colors of CMYG areoutput. Therefore, the image signals of the four colors of CMYG areconverted into image signals of the three colors of RGB by thecomplementary color-primary color conversion, so that an image signal ofeach color of the same RGB as that of the image pickup sensor 44 can beobtained.

The image pickup sensor 44 is driven and controlled by the image pickupcontrol unit 45. The control by the image pickup control unit 45 differsfor each mode. In the normal light mode, the image pickup control unit45 controls the image pickup sensor 44 so as to pick up an image of theobservation target illuminated with the normal light. Accordingly, a Bcimage signal is output from a B pixel of the image pickup sensor 44, aGc image signal is output from a G pixel, and an Rc image signal isoutput from an R pixel.

In the special light mode or the disease-related processing mode, theimage pickup control unit 45 controls the image pickup sensor 44 so asto pick up an image of the observation target illuminated with thespecial light. Accordingly, a Bs image signal is output from the B pixelof the image pickup sensor 44, a Gs image signal is output from the Gpixel, and an Rs image signal is output from the R pixel.

A correlated double sampling/automatic gain control (CDS/AGC) circuit 46performs correlated double sampling (CDS) and automatic gain control(AGC) on an analog image signal obtained from the image pickup sensor44. The image signal that has passed through the CDS/AGC circuit 46 isconverted into a digital image signal by an analog/digital (A/D)converter 48. The digital image signal after A/D conversion is input tothe processor apparatus 16.

The processor apparatus 16 comprises an image acquisition unit 50, adigital signal processor (DSP) 52, a noise reduction unit 54, an imageprocessing switching unit 56, an image processing unit 58, and a videosignal generation unit 60. The image processing unit 58 comprises anormal light image generation unit 62, a special light image generationunit 64, and a disease-related processing unit 66.

In the processor apparatus 16, programs related to various processingare stored in a program storage memory (not shown). With the programs inthe program storage memory to be executed by the processor, thefunctions of the image acquisition unit 50, the noise reduction unit 54,the image processing switching unit 56, the image processing unit 58,and a video signal generation unit 60 are realized. Along with this, thefunctions of the normal light image generation unit 62, the speciallight image generation unit 64, and the disease-related processing unit66 included in the image processing unit 58 are realized.

The image acquisition unit 50 acquires an image signal of an endoscopicimage, which is one of medical images that are input from the endoscope12. The acquired image signal is transmitted to the DSP 52. The DSP 52performs various signal processing such as defect correction processing,offset processing, gain correction processing, linear matrix processing,gamma conversion processing, demosaicing processing, and YC conversionprocessing, on the received image signal. In the defect correctionprocessing, a signal of a defective pixel of the image pickup sensor 44is corrected. In the offset processing, a dark current component isremoved from the image signal subjected to the defect correctionprocessing, and an accurate zero level is set. In the gain correctionprocessing, the image signal of each color after the offset processingis multiplied by a specific gain and the signal level of each imagesignal is adjusted. The image signal of each color after the gaincorrection processing is subjected to linear matrix processing forenhancing color reproducibility.

After that, the brightness and saturation of each image signal areadjusted by the gamma conversion processing. The image signal after thelinear matrix processing is subjected to the demosaicing processing(also referred to as isotropic processing or demosaicking processing),and a signal of the missing color of each pixel is generated byinterpolation. With the demosaicing processing, all the pixels have asignal of each color of RGB. The DSP 52 performs YC conversionprocessing on each image signal after demosaicing processing and outputsa brightness signal Y and a color difference signals Cb and Cr to thenoise reduction unit 54.

The noise reduction unit 54 performs noise reduction processing using,for example, a moving average method, a median filter method, on theimage signal subjected to the demosaicing processing by the DSP 52 andthe like. The image signal with reduced noise is input to the imageprocessing switching unit 56.

The image processing switching unit 56 switches a transmissiondestination of the image signal from the noise reduction unit 54 to anyone of the normal light image generation unit 62, the special lightimage generation unit 64, or the disease-related processing unit 66, onthe basis of the set mode. Specifically, in a case where the normallight mode is set, the image signal from the noise reduction unit 54 isinput to the normal light image generation unit 62. In a case where thespecial light mode is set, the image signal from the noise reductionunit 54 is input to the special light image generation unit 64. In acase where the disease-related processing mode is set, the image signalfrom the noise reduction unit 54 is input to the disease-relatedprocessing unit 66.

The normal light image generation unit 62 performs image processing fornormal light image, on the input Rc image signal, Gc image signal, andBc image signal for one frame. The image processing for normal lightimage includes color conversion processing such as 3×3 matrixprocessing, gradation conversion processing, and three-dimensional lookup table (LUT) processing, and structure enhancement processing such ascolor enhancement processing and spatial frequency enhancement. The Rcimage signal, the Gc image signal, and the Bc image signal subjected tothe image processing for normal light image are input to the videosignal generation unit 60 as a normal light image.

The special light image generation unit 64 performs image processing forspecial light image, on the input Rs image signal, Gs image signal, andBs image signal for one frame. The image processing for special lightimage includes color conversion processing such as 3×3 matrixprocessing, gradation conversion processing, and three-dimensional lookup table (LUT) processing, and structure enhancement processing such ascolor enhancement processing and spatial frequency enhancement. The Rsimage signal, Gs image signal, and Bs image signal subjected to imageprocessing for special light image are input to the video signalgeneration unit 60 as a special light image.

The disease-related processing unit 66 performs disease-relatedprocessing on the basis of a special light image which is one of medicalimages. Specifically, the disease-related processing unit 66 performs atleast one of calculating an index value for a stage of ulcerativecolitis, determining the stage of the ulcerative colitis, or determiningpathological remission or pathological non-remission of the ulcerativecolitis, on the basis of superficial vascular congestion, intramucosalbleeding, and extramucosal bleeding that are obtained from the speciallight image. Information regarding the determination result is input tothe video signal generation unit 60. Details of the disease-relatedprocessing unit 66 will be described later. In the first to thirdembodiments, a case where the disease-related processing unit 66determines pathological remission or pathological non-remission ofulcerative colitis will be described.

The video signal generation unit 60 converts the normal light image, thespecial light image, or the information regarding the determinationresult output from the image processing unit 58 into a video signal thatcan be displayed in full color on the monitor 18. The converted videosignal is input to the monitor 18. As a result, the normal light image,the special light image, or the information regarding the determinationresult is displayed on the monitor 18.

The details of the disease-related processing unit 66 will be describedbelow. As shown in FIGS. 7A to 7E, the inventors have found out thatulcerative colitis to be determined by the disease-related processingunit 66 changes the pattern of the vascular structure as the severityworsens. In a case where ulcerative colitis is in pathological remissionor ulcerative colitis does not occur, the pattern of superficial bloodvessels is regular (FIG. 7A), or some disturbance occurs in the patternregularity of the superficial blood vessels (FIG. 7B). On the otherhand, in a case where ulcerative colitis is in pathologicalnon-remission and the severity is mild, superficial blood vessels arelocally congested (FIG. 7C). Further, in a case where ulcerative colitisis in pathological non-remission and the severity is moderate,intramucosal bleeding occurs (FIG. 7D). Further, in a case whereulcerative colitis is in pathological non-remission and the severity ismoderate to severe, extramucosal bleeding occurs (FIG. 7E). Thedisease-related processing unit 66 determines pathological remission orpathological non-remission of ulcerative colitis on the basis of thespecial light image which is one of the medical images, by using thepattern change of the vascular structure.

Here, the “superficial vascular congestion” refers to a state in whichsuperficial blood vessels meander and gather, and in appearance on theimage, the intestinal gland (crypt) is surrounded by many superficialblood vessels (see FIG. 8). The “intramucosal bleeding” refers tobleeding in the mucosal tissue (see FIG. 7D), and is required to bediscriminated from bleeding into the intracavity. The “intramucosalbleeding” refers to bleeding not in the interior of the mucosa and inthe intracavity (lumen, cavity of fold), in appearance on the image. The“extramucosal bleeding” refers to a small amount of blood into thelumen, visible blood that oozes out of the mucosa or the lumen in frontof the endoscope after cleaning of the lumen, or blood in the lumen thatoozes through bleeding mucosa.

The disease-related processing unit 66 performs disease-relatedprocessing on the basis of the special light image. Specifically, asshown in FIG. 9, the disease-related processing unit 66 has a bloodvessel extraction unit 70 that extracts blood vessels, such as asuperficial blood vessel, intramucosal bleeding, and extramucosalbleeding, from the special light image, and a determination unit 72 thatdetermines pathological remission or pathological non-remission ofulcerative colitis on the basis of the extracted blood vessel.

The blood vessel extraction unit 70 extracts, as a blood vessel,superficial vascular congestion, intramucosal bleeding, and extramucosalbleeding on the basis of at least one of frequency response orbrightness values obtained from the special light image. Thedetermination unit 72 determines pathological remission or pathologicalnon-remission of ulcerative colitis by using an index value that isobtained on the basis of an area of the superficial vascular congestion,an area of the intramucosal bleeding, and an area of the extramucosalbleeding of the special light image. The index value is preferably avalue that is obtained by individually adding the areas of thesuperficial vascular congestion, the areas of the intramucosal bleeding,and the areas of the extramucosal bleeding. Specifically, thedetermination unit 72 determines that ulcerative colitis is inpathological remission in a case where the index value is less than athreshold value, and that the ulcerative colitis is in pathologicalnon-remission in a case where the index value is a threshold value ormore.

The information regarding the determination by the determination unit 72is displayed on the monitor 18 and used for the determination of thepathological remission or the pathological non-remission of ulcerativecolitis by the user. In a case where the determination unit 72determines that ulcerative colitis is in pathological remission, amessage of the determination result is displayed on the monitor 18, asshown in FIG. 10. In a case where the information regarding thedetermination is displayed, it is preferable to superimpose and displaythe special light image that is used for the determination by thedetermination unit 72.

In order to improve the accuracy of the determination by thedetermination unit 72, it is preferable to use a special light image inwhich the observation target is magnified at an appropriatemagnification ratio. Specifically, as in the special light of thepresent embodiment, it is preferable to use a special light image whichis obtained by picking up an image of the observation target illuminatedwith illumination light including short-wavelength narrowband light, theobservation target being magnified at a first magnification ratio ormore and less than a second magnification ratio, which is more than thefirst magnification ratio. Here, the narrowband light refers to lighthaving a half-width of 40 nm or less, light emitted as it is from asemiconductor light source such as an LED or LD (for example, “violetlight V” of the first embodiment and “violet laser light” and “bluelaser light” of the third embodiment), or light in which light frombroadband light such as white light is cut out by a filter (for example,“blue narrowband light” and “green narrowband light” of the secondembodiment). In a case where blood vessels are extracted by the bloodvessel extraction unit 70 for the special light image based onillumination light including short-wavelength narrowband light, theextraction accuracy of a superficial blood vessel, intramucosalbleeding, and extramucosal bleeding extracted by the blood vesselextraction unit 70 is improved as compared with the accuracy of theblood vessel extraction that is performed for an image based on lightnot including short-wavelength narrowband light. Further, it ispreferable that the first magnification ratio is five times or more, andthe second magnification ratio is 135 times (in a case where the monitor18 is 19 inches) to 230 times (in a case where the monitor 18 is 32inches) or less.

The reason for setting the first magnification ratio to five times is asfollows. In a case where far-field imaging or imaging with lowmagnification ratio in which the thickness of the microvessel isdecreased into one pixel or less of the monitor 18 is performed when amicrovessel, such as a superficial blood vessel, intramucosal bleeding,and extramucosal bleeding, is extracted, the thickness of the bloodvessel is extracted as one pixel even though the actual thickness of theblood vessel is one pixel or less, when the blood vessel is extracted bythe blood vessel extraction unit 70. For example, in a case where avascular density indicating the ratio of the blood vessel to a 72-pixelregion which is a specific pixel region is calculated, as shown in (A)of FIG. 11, although the blood vessel VC having a thickness of smallerthan one pixel (represented by “PX”, the same applies hereinafter)belongs to actually six pixels and the vascular density is 6/72, thethickness of the blood vessel VC having an actual thickness of less thanone pixel is also extracted by the blood vessel extraction unit 70 asone pixel and as shown in (B) of FIG. 11, the blood vessel VC may beextracted as 12 pixels and the vascular density may become 12/72. Thatis, in a case where the blood vessel VC having a thickness of less thanone pixel is extracted as one pixel, a difference from the actual areaof the blood vessel occurs. This is one of the causes of lowering theaccuracy of the determination result by the determination unit 72.

Therefore, it is preferable to magnify the observation target at thefirst magnification ratio at which the thickness of the blood vessel ismade one or more pixels. That is, in a case where a vascular densityindicating the ratio of the blood vessel to a 288-pixel region which isa specific pixel region is calculated, and as shown in (A) of FIG. 12,the blood vessel VC belongs to actually 24 pixels and a vascular densityis 24/288, the blood vessel is extracted from the special light image inwhich the observation target is magnified at the first magnificationratio at which the thickness of the blood vessel VC is made one or morepixels, so that as shown in (B) of FIG. 12, the blood vessel VC may beextracted as 24 pixels and the vascular density may become 24/288, likethe actual size. As a result, since the area of the extracted bloodvessel is the same as the actual area, the accuracy of the determinationresult by the determination unit 72 can be improved.

In a case where the monitor 18 that displays the special light image isa 19-inch 8K monitor, the size of one pixel is 54 μm. Therefore, inorder to put a microvessel having a thickness of 10 μm onto a pluralityof pixels, which are one or more pixels, the first magnification ratiois preferably 54 μm/10 μm=5.4 times≈5 times or more.

The reason for setting the second magnification ratio to less than 135times is as follows. In a case where the index value that is obtained onthe basis of the area of the superficial vascular congestion, the areaof the intramucosal bleeding, and the area of extramucosal bleeding anda pathological score (the larger the score, the higher the severity ofthe disease) of a disease corresponding to the index value are plottedon a two-dimensional graph, and as shown in FIG. 13, the secondmagnification ratio is 40 times, which is less than 135 times, pointsPT's of which the pathological scores are in a pathological remissionregion are distributed in an index value of 20000 or less. On the otherhand, points PT's of which the pathological scores are in a pathologicalnon-remission region are distributed in an index value of 20000 or more.That is, with the index value, a pathological remission group includingthe points PT's in the pathological remission region and a pathologicalnon-remission group including the points PT's in the pathologicalnon-remission region can be distinguished from each other. Accordingly,the determination by the determination unit 72 can be made.

On the other hand, as shown in FIG. 14, in a case where the secondmagnification ratio is 135 times, it is difficult to distinguish thepoints PT's distributed in the pathological remission region and thepoints PT's distributed in the pathological non-remission region, byusing the index value. For this reason, in a case where the secondmagnification ratio is 135 times, it is difficult to determine thepathological remission or the pathological non-remission of ulcerativecolitis by using the index value. Therefore, the second magnificationratio is preferably less than 135 times. Note that, in a case where themonitor 18 is 19 inches, the second magnification ratio is preferablyless than 135 times, but in a case where the monitor 18 is 19 inches ormore, the second magnification ratio may be 135 times or more. Forexample, in a case where the monitor 18 is 32 inches, a secondmagnification ratio in the case of 32 inches into which the secondmagnification ratio in the case of 19 inches is converted is 230 timesor less (135 times (in the case of 19 inches)×39.83 (in the case of 32inches width)/23.65 (in the case of 19 inches width)).

As shown in FIG. 15, in a case where there are blood vesselirregularities in which the vascular density differs depending on theposition in the special light image, the areas of the blood vesselextracted in the magnified region are different between a region RH inwhich the vascular density is locally high and a region RL in which thevascular density is locally low. In this case, in a case where thesecond magnification ratio exceeds 135 times to 230 times, the magnifiedimage may include only one of the region RL or the region RH, not theaverage region of the region RL and the region RH. In this case, withthe blood vessel extraction, only local blood vessel information can beacquired and average blood vessel information as the entire speciallight image cannot be obtained. As a result, the accuracy of thedetermination by the determination unit 72 is decreased.

Next, a series of flow of a disease-related processing mode will bedescribed with reference to a flowchart shown in FIG. 16. In a casewhere a mode is switched to the disease-related processing mode, theobservation target is irradiated with special light includingshort-wavelength narrowband light. Further, the zoom operation portion12 h is operated, to make the magnification ratio of the observationtarget the first magnification ratio or more and less than the secondmagnification ratio. The endoscope 12 picks up an image of theobservation target illuminated with special light to obtain a speciallight image that is one of endoscopic images (medical images). The imageacquisition unit 50 acquires the special light image from the endoscope12.

The blood vessel extraction unit 70 extracts, as a blood vessel,superficial vascular congestion, intramucosal bleeding, and extramucosalbleeding on the basis of frequency response or brightness valuesobtained from the special light image. The determination unit 72determines pathological remission or pathological non-remission ofulcerative colitis by using an index value that is obtained on the basisof an area of the superficial vascular congestion, an area of theintramucosal bleeding, and an area of the extramucosal bleeding of thespecial light image. Information regarding the determination by thedetermination unit 72 is displayed on the monitor 18.

Second Embodiment

In the second embodiment, a broadband light source, such as a xenonlamp, and a rotation filter are used to illuminate the observationtarget, instead of the four-color LEDs 20 a to 20 e shown in the firstembodiment. Further, an image of the observation target is picked up bya monochrome image pickup sensor, instead of the color image pickupsensor 44. Other than that, the same as the first embodiment applies.

As shown in FIG. 17, in an endoscope system 100 of the secondembodiment, the light source apparatus 14 is provided with a broadbandlight source 102, a rotation filter 104, and a filter switching unit105, instead of the four-color LEDs 20 a to 20 e. Further, the imagepickup optical system 30 b is provided with a monochrome image pickupsensor 106 without a color filter, instead of the color image pickupsensor 44.

The broadband light source 102 is a xenon lamp, a white LED, or thelike, and emits white light having a wavelength range ranging from blueto red. The rotation filter 104 is provided with a filter for normallight mode 107 and a filter for special light mode and disease-relatedprocessing mode 108 in order from the inside (see FIG. 18). The filterswitching unit 105 moves the rotation filter 104 in a radial direction,and inserts the filter for normal light mode 107 into the optical pathof white light in a case where the normal light mode is set by the modechangeover SW 12 f, and inserts the filter for special light mode anddisease-related processing mode 108 into the optical path of white lightin a case where the special light mode or the disease-related processingmode is set.

As shown in FIG. 18, the filter for normal light mode 107 is providedwith a B filter 107 a that transmits broadband blue light B of whitelight, a G filter 107 b that transmits broadband green light G of whitelight, and an R filter 107 c that transmits broadband red light R ofwhite light, along a circumferential direction. Therefore, in the normallight mode, with the rotation of the rotation filter 104, theobservation target is alternately irradiated with the broadband bluelight B, the broadband green light G, and the broadband red light R, asnormal light.

The filter for special light mode and disease-related processing mode108 is provided with a Bn filter 108 a that transmits blue narrowbandlight of white light and a Gn filter 108 b that transmits greennarrowband light of white light, along the circumferential direction.Therefore, in the special light mode or the disease-related processingmode, with the rotation of the rotation filter 104, the observationtarget is alternately irradiated with the blue narrowband light and thegreen narrowband light as short-wavelength narrowband light, as speciallight. The wavelength range of the blue narrowband light is preferably400 to 450 nm, and the wavelength range of the green narrowband light ispreferably 540 to 560 nm.

In the endoscope system 100, in the normal light mode, an image of theobservation target is picked up by the monochrome image pickup sensor106 each time the observation target is illuminated with the broadbandblue light B, the broadband green light G, or the broadband red light R.Accordingly, a Bc image signal, a Gc image signal, and an Rc imagesignal can be obtained. A normal light image is generated by the samemethod as in the first embodiment, on the basis of the three-color imagesignals.

In the endoscope system 100, in the special light mode or thedisease-related processing mode, an image of the observation target ispicked up by the monochrome image pickup sensor 106 each time theobservation target is illuminated with the blue narrowband light or thegreen narrowband light. Accordingly, a Bs image signal and a Gs imagesignal can be obtained. A special light image is generated by the samemethod as in the first embodiment, on the basis of the two-color imagesignals.

Third Embodiment

In the third embodiment, a laser light source and a phosphor are used toilluminate the observation target, instead of the four-color LEDs 20 ato 20 e shown in the first embodiment. In the following, only the partsdifferent from the first embodiment will be described, and thedescription of the parts substantially the same as those of the firstembodiment will be omitted.

As shown in FIG. 19, in an endoscope system 200 of the third embodiment,the light source unit 20 of the light source apparatus 14 is providedwith a violet laser light source unit 203 (denoted by “405LD”, the LDrepresents a “laser diode”) that emits violet laser light having acentral wavelength of 405±10 nm, which corresponds to short-wavelengthnarrowband light, and a blue laser light source unit 204 (denoted by“445LD”) that emits blue laser light having a central wavelength of445±10 nm, instead of the four-color LEDs 20 a to 20 e. The lightemitted from semiconductor light emitting elements of the light sourceunits 204 and 206 is individually controlled by the light source controlunit 208.

In the normal light mode, the light source control unit 208 makes theblue laser light source unit 204 turned on. On the other hand, in thespecial light mode or the disease-related processing mode, the lightsource control unit 208 makes the violet laser light source unit 203 andthe blue laser light source unit 204 turned on at the same time.

The half-width of the violet laser light or the blue laser light ispreferably about ±10 nm. Further, as the violet laser light source unit203 or the blue laser light source unit 204, a broad area typeInGaN-based laser diode can be used, and an InGaNAs-based laser diode ora GaNAs-based laser diode can also be used. Further, as the lightsource, a light emitting body such as a light emitting diode may beused.

The illumination optical system 30 a is provided with a phosphor 210 towhich violet laser light or blue laser light from the light guide 25 isincident, in addition to the illumination lens 32. The phosphor 210 isexcited by blue laser light and emits fluorescence. Therefore, the bluelaser light corresponds to excitation light. Further, a part of the bluelaser light is transmitted without exciting the phosphor 210.

Here, in the normal light mode, since the blue laser light is mainlyincident on the phosphor 210, as shown in FIG. 20, the observationtarget is illuminated with normal light in which the blue laser lightand the fluorescence emitted from the phosphor 210 excited by the bluelaser light are combined. In a case where an image of the observationtarget illuminated with the normal light is picked up by the imagepickup sensor 44, a normal light image including a Bc image signal, a Gcimage signal, and an Rc image signal can be obtained.

Further, in the special light mode or the disease-related processingmode, since violet laser light and blue laser light are simultaneouslyincident on the phosphor 210, as shown in FIG. 21, pseudo white lightincluding the fluorescence emitted from the phosphor 210 excited by theviolet laser light and the blue laser light is emitted, in addition tothe violet laser light and the blue laser light, as the special light.In a case where an image of the observation target illuminated with thespecial light is picked up by the image pickup sensor 44, a speciallight image including a Bs image signal, a Gs image signal, and an Rsimage signal can be obtained. The pseudo white light may be acombination of violet light V, blue light B, green light G, and redlight R emitted from V-LED 20 a, B-LED 20 b, G-LED 20 c, and R-LED 20 d.

As the phosphor 210, a phosphor that includes a plurality of types ofphosphors (for example, a YKG-based phosphor or a phosphor such asBaMgAl₁₀O₁₇ (BAM)) which absorb a part of blue laser light and whichexcite and emit green color to yellow color is preferably used. As inthe present configuration example, in a case where a semiconductor lightemitting element is used as an excitation light source for the phosphor210, high-intensity white light can be obtained with high luminousefficiency, the intensity of white light can be easily adjusted, and thechange of the color temperature and chromaticity of white light can besuppressed to a small extent.

In the above-described embodiment, the present invention is applied toan endoscope system that performs processing for an endoscopic image,which is one of medical images, but the present invention can also beapplied to a medical image processing system that performs processingfor medical images other than the endoscopic image. The presentinvention can also be applied to a diagnosis support apparatus that isused to provide diagnostic support to a user using a medical image. Thepresent invention can also be applied to a medical service supportapparatus that is used to support medical service, such as a diagnosticreport, using a medical image.

For example, as shown in FIG. 22, a diagnosis support apparatus 600 isused in combination with a modality, such as a medical image processingsystem 602, and picture archiving and communication systems (PACS) 604.Further, as shown in FIG. 23, a medical service support apparatus 610 isconnected to various examination apparatuses, such as a first medicalimage processing system 621, a second medical image processing system622, . . . , and an N-th medical image processing system 623, via anynetwork 626. The medical service support apparatus 610 receives medicalimages from the first to N-th medical image processing systems 621, 622,. . . , to 623, and supports the medical service on the basis of thereceived medical images.

In the above-described embodiment, as a hardware structure of aprocessing unit that executes various processing, such as the normallight image generation unit 62, the special light image generation unit64, the disease-related processing unit 66, the blood vessel extractionunit 70, and the determination unit 72, which are included in the imageprocessing unit 58, various processors as described below are used. Thevarious processors include, for example, a central processing unit(CPU), which is a general-purpose processor that executes software(programs) to function as various processing units, a programmable logicdevice (PLD), such as a field programmable gate array (FPGA), which is aprocessor having a changeable circuit configuration after manufacture,and a dedicated electrical circuit, which is a processor having adedicated circuit configuration designed to execute various processing.

One processing unit may be constituted of one of the various processorsor may be constituted of a combination of two or more processors of thesame type or different types (for example, a combination of a pluralityof FPGAs and a combination of a CPU and an FPGA). Further, the pluralityof processing units may constitute one processor. A first example of theconfiguration in which the plurality of processing units are constitutedof one processor is an aspect in which one or more CPUs and software arecombined to constitute one processor and the processor functions as aplurality of processing units. A representative example of the aspect isa computer such as a client or server. A second example of theconfiguration is an aspect in which a processor that implements all ofthe functions of a system including the plurality of processing unitswith one integrated circuit (IC) chip is used. A representative exampleof the aspect is a system on chip (SoC). As described above, as thehardware structure of various processing units, one or more of thevarious processors are used.

Furthermore, as the hardware structure of the various processors, morespecifically, an electrical circuit (circuitry) in which circuitelements, such as semiconductor elements, are combined are used.

EXPLANATION OF REFERENCES

10: endoscope system

12: endoscope

12 a: insertion part

12 b: operation part

12 c: bendable part

12 d: distal end part

12 e: angle knob

12 f: mode changeover switch

12 g: still image acquisition instruction portion

12 h: zoom operation portion

14: light source apparatus

16: processor apparatus

18: monitor

19: user interface

20: light source unit

20 a: V-LED

20 b: B-LED

20 c: G-LED

20 d: R-LED

21: light source control unit

23: optical path coupling unit

25: light guide

30 a: Illumination optical system

30 b: image pickup optical system

32: illumination lens

42: objective lens

43: zoom lens

44: image pickup sensor

45: image pickup control unit

46: CDS/AGC circuit

47: magnification ratio display section

48: A/D converter

49: magnification ratio display section

49 a: horizontal bar

49 b: upper limit display bar

50: image acquisition unit

52: DSP

54: noise reduction unit

56: image processing switching unit

58: image processing unit

60: video signal generation unit

62: normal light image generation unit

64: special light image generation unit

66: disease-related processing unit

70: blood vessel extraction unit

72: determination unit

100: endoscope system

102: broadband light source

104: rotation filter

105: filter switching unit

106: image pickup sensor

107: filter for normal light mode

107 a: B filter

107 b: G filter

107 c: R filter

108: filter for special light mode and disease-related processing mode

108 a: Bn filter

108 b: Gn filter

200: endoscope system

203: violet laser light source unit

204: blue laser light source unit

208: light source control unit

210: phosphor

600: diagnosis support apparatus

602: medical image processing system

604: PACS

610: medical service support apparatus

621: first medical image processing system

622: second medical image processing system

623: N-th medical image processing system

626: network

Bx1, Bx2, Bx3, Bx4: box

V: violet light

B: blue light

G: green light

R: red light

SC: specific color

VC: blood vessel

PX: pixel

PT: point

RH, RL: region

What is claimed is:
 1. An image processing apparatus comprising: aprocessor configured to: acquire a medical image which is obtained bypicking up an image of an observation target illuminated withillumination light including short-wavelength narrowband light, theobservation target being magnified at a first magnification ratio ormore and less than a second magnification ratio that is more than thefirst magnification ratio; and perform processing related to a diseaseon the basis of the medical image.
 2. The image processing apparatusaccording to claim 1, wherein magnification of the observation target isperformed at the first magnification ratio, to make a thickness of ablood vessel that is included in the observation target magnified to oneor more pixels.
 3. The image processing apparatus according to claim 1,wherein the first magnification ratio is five times or more.
 4. Theimage processing apparatus according to claim 1, wherein the secondmagnification ratio is 230 times or less.
 5. The image processingapparatus according to claim 1, wherein the illumination light is violetlight of which a central wavelength or a peak wavelength includes awavelength of 410 nm, as the short-wavelength narrowband light.
 6. Theimage processing apparatus according to claim 1, wherein theillumination light is blue narrowband light and green narrowband light,as the short-wavelength narrowband light, and the medical image isobtained by picking up an image of the observation target that isalternately illuminated with the blue narrowband light and the greennarrowband light.
 7. The image processing apparatus according to claim1, wherein the illumination light is pseudo white light including theshort-wavelength narrowband light and fluorescence obtained byirradiating a phosphor with excitation light.
 8. The image processingapparatus according to claim 1, wherein the illumination light includesviolet light as the short-wavelength narrowband light and blue light,green light, or red light.
 9. The image processing apparatus accordingto claim 1, wherein the processor further configured to perform at leastone of calculating an index value for a stage of ulcerative colitis,determining the stage of the ulcerative colitis, or determiningpathological remission or pathological non-remission of the ulcerativecolitis, on the basis of at least one of superficial vascularcongestion, intramucosal bleeding, or extramucosal bleeding that isobtained from the medical image.
 10. The image processing apparatusaccording to claim 1, wherein the processor further configured tocalculate an index value related to a disease on the basis of themedical image, and the index value distinguishes between pathologicalremission and pathological non-remission of a disease in atwo-dimensional graph showing the correspondence between the index valueand a severity of the disease corresponding to the index value.
 11. Anendoscope system comprising: a light source unit that emits illuminationlight including short-wavelength narrowband light; and a processorconfigured to: acquire a medical image which is obtained by picking upan image of an observation target illuminated with illumination lightincluding short-wavelength narrowband light, the observation targetbeing magnified at a first magnification ratio or more and less than asecond magnification ratio that is more than the first magnificationratio; and perform processing related to a disease on the basis of themedical image.
 12. An operation method of an image processing apparatus,the method comprising: acquiring a medical image which is obtained bypicking up an image of an observation target illuminated withillumination light including short-wavelength narrowband light, theobservation target being magnified at a first magnification ratio ormore and less than a second magnification ratio that is more than thefirst magnification ratio; and performing processing related to adisease on the basis of the medical image.